Coolant in the oil. Countdown to a rebuild has begun?
 

The last couple of weeks the car acted like it was flooded on start up but different. Like it was running on one rotor. (I moved the car 10 feet to wash it once and I could barely get it started. Learned my lesson that time.)

I give it a bit of throttle and it clears up and runs great with no issues.

What sort of has me worried is this. After reading this thread:

Bad coolant seal or running rich?

Sgtblue's description of a coolant seal going bad.

My car has been using some coolant the last few weeks. Maybe 6-10oz to top it off at the water neck. I had a coolant buzzer that went off, so I have been checking it each time I drive it.

Tonight, I realized I hadn't checked the oil in a while. Needed to top it up and when I pulled the filler cap, white foam all along the neck. Clearly I have some amount of coolant in the oil. The foam wasn't there a month ago when I changed the oil. No oil that I can see in the coolant. No sweet smell on startup, I am running 50/50. I don't drive it short distances, I try to drive it for at least 20mins + when I take it out.

My car sat in storage for a long time (5-8 years?) before the guy I bought it from got it back up and running (Oct2014). Chassis has 130k, I was told the motor was replaced at 90k, possibly with a used motor. I feel like I am driving around in a ticking time-bomb. :)

Still learning about these motors. Car had/has decent compression (109-113psi) but I guess if it has to come apart it has to be gone through no matter what. Do these motors have main bearings? What other components will be adversely affected if I continue to drive it until the seal inevitably fails.

The car still drives fine with no other issues....yet. Pulls hard, etc.

Thanks for any info


https://cimg6.ibsrv.net/gimg/www.rx7...f173474850.jpg


https://cimg2.ibsrv.net/gimg/www.rx7...21c01ee189.jpg

The condensation in the oil filler neck is probably unrelated to your missing coolant. More testing is required. Champagne test, coolant pressure leak down..etc.

Yeah...that filler neck is no big deal. Now if you drain the oil and it is milky and/or a bunch of water comes out...yeah, then your fawked.
But as you already know in your heart, you just haven't embraced the full horror of it yet, you more than likely have coolant seals leaking. Most of us have been there, done that at one point or another.

Memorial Day weekend, no foam in the oil when I drained it. None on the dip stick now but that probably doesn't mean much. But I was down about a 1/3 of a quart after a few hundred miles. If there was that much water in the oil I would suspect it would read closer to the top.

Will have to look up the champagne test, assume that's the one where you pull the plug and crank the engine looking for water to blow out the spark plug hole. May have to visit a local rotary shop and have the leak down test done.

Every time I leave a parking spot I check for fluids. LOL The car leaves nothing behind but a few drops of oil. I replaced the rad and all the hoses in Feb, other than the hose to the overflow and the one to the TB.

Where's the oil drops coming from?

Typically what happens when the coolant seals are failing is the combustion process overpressurizes the coolant system, forcing coolant into and out the overflow tank.


Then there isn't any coolant available as the car cools to suck back into the system via the thermosiphon effect, hence you see the loss.


How is your overflow tank? Fill it up to the required level once you have the rest of the system filled. There are little hash-marks on its dipstick. Go out for a quick drive, get it up to temperature, then come back and check the tank. If the system is working correctly, it should be HIGHER in the tank as the volume of coolant has expanded due to the heat of it (this is why they are also referred to as "expansion tanks"), but as the car cools, it should draw out of the expansion/overflow tank and return it to the level you filled it to.

Where doesn't it come from? :lol:

Oil pan mostly. Have the brace haven't had the time to put it in. Rear main seal replaced with clutch. Filter stand O-rings replaced. Sending unit resealed. Somewhere higher on the motor than those two things is leaking, towards the back. Oil Injectors? Oil filler neck? Front right of the motor, OMP? Not too bad over there, probably needs new washers. I have a nice coating of oil all the way back past my mid-pipe so at least I know my car isn't going to rust anytime soon. :)

Will check this closer the next time out. Its got coolant in it but I haven't been monitoring it. I know how the system is supposed to function so you are right starting with the simple things is always the best course. AST is new, caps are both new. Only the one on the AST is a pressure cap.

I have about 20 years knowledge of working on all type of piston cars. LOL. NOt a mechanic, just an enthusiast.

There needs to be a .9 bar pressure cap on the filler, also.

Why would I need pressure caps on both? I thought when running an AST you only ran one on the AST.

Factory setup, remember what the AST's function is.

Hmm, now I am confused. When I first bought the car it didn't have an AST. It had what I guess was an ASP delete, Turbo II setup on the water neck with a .9 bar cap. A lot of gurgling in the heater core.

So I added the AST and from the research I had done, thought I needed just a cap for the water neck. The mazda parts diagram I was looking at showed a non-press cap for the water neck, so that's what I ordered. I still have the other .9 bar cap.

A pressure cap will fit the oem filler neck location, but doesn't do anything extra beyond sealing the top closed just like a factory fill cap does.

Nope.


It won't hurt anything, but it isn't supposed to be there.

Did some more investigating. Looking through the RH duct opening in the bumper, it looks like there is some residual fluid below the overflow tank. Could have been there a long time or more recently, hard to tell. Something to check the next time out. Also, the coolant level sitting on the expansion tank cold is at the top of the hash marks. I can also see about a 1/4" of brown crud in the tank. I flushed out the motor and heater core, didn't think to hit the plastic tank. Being that's its buried I assume the only way to get it out would be to pull the front bumper? Or is there another way.

So I guess there is still the potential that the coolant is expanding over to the tank and not returning as the system cools as it should. Boy I sure hope so. Will post back, probably not until next week.

You can get to the Coolant overflow tank by removing the front passenger side wheel and fender liner..... leave the bumper on ;)

Phew! I always assume the worst with this car, but I must persevere. :)

Yes, carefully inspect the hoses between the AST and overflow. Or even just replace them, probably time for that to be done anyway even if you do end up needing a rebuild. The slightest pinhole leak will result in failure to pull coolant back into the engine.

Pulled the expansion tank. There was definitely a few drips of coolant on the lower tray and a moist color to the general area. Signs of overflow while moving. Will order the hoses tomorrow.

The small black grommet next to the opening the filler neck slides into is just an overflow for the tank, correct? I am not missing anything else?


https://cimg7.ibsrv.net/gimg/www.rx7...b1aa0772f3.jpg

Nothing goes there that I know of.

If coolant is coming out of that hole then you have too much coolant!

Right, IF. I originally topped the system off a few times because my coolant buzzer was going off. The coolant must have been going somewhere and I am going to assume it was not being drawn back into the system. But I never saw coolant under the car, in my garage or elsewhere. Will get it buttoned back up this week and pay close attention to this area as well as the exact levels in the overflow.

Yeah...I went back thru the parts diagram and came to the same conclusion, lol!


Sorry, o.p., if I caused any confusion... :blush:

NP, I thought I was right either way. LOL

It will be a long time before I claim to be any kind of rotary expert that's for sure.

Update
 

Pulled the fender liner and expansion tank and cleaned it out.

Installed new AST to tank hose, was a little short for the location of my AST, so I used one of the white plastic couplers from the old hose to extend it 5" or so.

Added some coolant to the expansion tank, ended up almost halfway between L and F or whatever the letters were on the dipstick. Marked the tank with a sharpie.

Topped off the water neck, to the top.

Started the car and my coolant buzzer came on (son-of-a). Popped the cap off, car had been idling maybe 2 mins, a small amount of coolant spilled out the top, put the cap back on, buzzer still on.

Started driving, buzzer shut off after 4 mins or so.

Drove on the HW for about 30 mins. Pulled in the garage and shut her down. Listened /watched the coolant expand into the tank. It went up about an inch and a half which ended up a notch or two above full. Marked the tank with a sharpie.

Car has been sitting for 3 hours. Water neck is still 100+ degree, infrared thermo.

Expansion tank level has now dropped down almost half an inch.

Will check the water neck level tomor when its dead cold.

just a cross the T question, but since the water level sensor is right under the cap on the thermostat, that is the one you're checking?